This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This study is assessing the effect of 1 month of paroxetine treatment on cardiovascular response and subjective discomfort during 2 mental stress tasks in smokers immediately after smoking a cigarette. Each subject receives one month of either paroxetine or placebo after which they return to the GCRC for a visit during which cardiovascular response is measured while performing two tasks expected to result in some mental stress. These tasks consist of giving a short speech and performing a mental arithmetic task. For the following month, subjects receive the alternate treatment after which response to the stress tasks is measured again.